This application relates generally to a chemical synthetic method and, more particularly, to a method for converting ether groups to hydroxyl groups and ester groups to acid groups.
It is known in the art to convert ether groups in compounds to hydroxyl groups by reacting the compound with boron tribromide in a solvent such as methylene chloride, typically at a temperature of -78.degree. C. This reaction has been taught for converting dye developer percursors, which are blocked with ether groups such as methoxy or benzyloxy, to dye developers which are useful in photographic applications.
This reaction is not completely satisfactory because in some instances the borate complex intermediate precipitates from solution before the reaction is complete, thus leading to significantly lower yields of pure product. Raising the temperature to deal with the solubility considerations does not necessarily overcome this disadvantage because boron tribromide is a strong Lewis acid and significant amounts of decomposition products can be encountered at the elevated temperatures.
The present invention is drawn to a method for converting ether groups to hydroxyl groups and ester groups to acid groups which proceeds under mild reaction conditions and which typically involves the formation of soluble intermediates.